FIG. 7 is an enlarged view of an insulating substrate 20 having a prescribed wiring pattern with a semiconductor chip 10 mounted by a so-called chip-on-board method. In an example of the chip-on-board method, an anisotropically conductive film 30 is interposed between insulating substrate 20 having conductor bumps 21 formed protruding upward and semiconductor chip 10 having electrode bumps 11 protruded from a main surface 10a, and these are heated and pressed so that conductor bumps 21 and electrode bumps 11 are conducted and connected.
As can be seen best from FIG. 7, anisotropically conductive film 30 has such a structure in that conductive particles 32 are dispersed in an adhesive resin film 31, and conductor bumps 21 and electrode bumps 11 are conducted and connected to each other as conductive particles 32 are interposed therebetween. An area of the main surface 10a of semiconductor chip 10 where electrode bumps 11 are not formed is adhered to insulating substrate 20 by the adhesiveness of resin film 31 provided when anisotropically conductive film 30 is heated, melt and thereafter solidified. At this time, the conductive particles 32 are dispersed in resin film 31 and separate from each other, and therefore insulation in this region is maintained. In the above described method of mounting, by only a simple operation of pressing semiconductor chip 10 and insulating substrate 20 to each other with anisotropically conductive film 30 interposed, it is possible to mount semiconductor chip 10 on insulating substrate 20 while attaining electrical conduction only at necessary portions. Therefore, as compared with mounting of semiconductor chip 10 on insulating substrate 20 through so called chip bonding and wire bonding, the method is very simple and convenient.
When semiconductor chip 10 is to be mounted on insulating substrate 20 utilizing anisotropically conductive film 30 however, it is necessary to prepare very small anisotropically conductive film having 4 sides each being about a few mm corresponding to the size of semiconductor chip 10 to be mounted, in the same number as the number of semiconductor chips 10 to be mounted. Further, prior to mounting of semiconductor chips 10, it is necessary to place anisotropically conductive films 30 one by one on conductor bumps 21 of insulating substrate 20 or to stick the films one by one on the main surface 10a of semiconductor chips 10. Thus, the conventional method of mounting utilizing anisotropically conductive film 30 has poor workability in preparation preceding mounting of the semiconductor chips 10.
In view of the foregoing, a method has been proposed in which anisotropically conductive film 30 is stuck entirely over a circuit element forming region of a semiconductor wafer on which a plurality of circuit elements, which are to be the semiconductor chips 10, are formed, and the anisotropically conductive film 30 is diced simultaneously with dicing of the circuit elements. In the above described method, when the circuit elements are divided into individual semiconductor chips 10, anisotropically conductive film 30 is stuck on main surface 10a, and the method has an advantage that any special preparation is not necessary prior to mounting of the semiconductor chip 10.
Generally, a semiconductor wafer has so called scribe lines formed at appropriate positions, and the wafer is diced into circuit elements by a diamond cutter, for example, using the scribe lines as reference marks. The scribe line is formed, for example, simultaneously with the step of forming a pattern of a passivation film. Now, as described above, anisotropically conductive film 30 has such a structure in that a number of conductive particles 32 are dispersed in resin film 31. Therefore, the color of anisotropically conductive film 30 is milky white. When anisotropically conductive film 30 is stuck on the semiconductor wafer, it becomes necessary to recognize silver scribe lines formed of SiN or the like through milky white anisotropically conductive film. This causes difficulty in visually recognizing the scribe lines, and hence difficulty in dicing the circuit elements to obtain desired semiconductor chips 10.